Converts the Expr to an array of the requested type and depth.
Some Exprs represent large lists or arrays of integers or reals. This method is the only efficient way of extracting the raw array data from out of the Expr. To preserve the immutability of Exprs, however, the returned array is a copy of the Expr's internal array data.
|ArgumentException||If depth > 2 or the requested type is not supported.|
|ExprFormatException||If the Expr cannot be converted to this format.|